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INTRODUCTION TO PYTHON LISTS

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INTRODUCTION TO PYTHON LISTS

INTRODUCTION

  • Lists in Python are ordered set of elements.
  • List elements are mutable, i.e. we can change the elements in the list
  • List can store elements of different data types like integer, decimal, string, boolean, another list, sets etc.
  • They are enclosed within square brackets([]).
  • If there is no element in the list then square bracket will be empty.
  • List in Python can contain duplicate elements

LIST ELEMENT DATA TYPE

Checking the data type of a list.

# LIST data type example

str_list = ['Python', 'Java', 'C', 'C++', 'XML', 'PHP']

print("\nData type of list str_list -> ", type(str_list))
print("\nElement of list str_list -> ", str_list)

INTRODUCTION TO PYTHON LISTS : Output

Data type of list str_list ->  <class 'list'>

Element of list str_list ->  ['Python', 'Java', 'C', 'C++', 'XML', 'PHP']

Data type of elements in the list can be of any data type.

STRING LIST

String lists containing all the string elements.

# String list example

str_list = ['Python', 'Java', 'C', 'C++', 'XML', 'PHP']

print("\nString list contains -> ", str_list)

INTRODUCTION TO PYTHON LISTS : Output

String list contains ->  ['Python', 'Java', 'C', 'C++', 'XML', 'PHP']

In the above example print command just has printed all the elements in the order they have placed inside the list. Now if we change the order in the list then the printing order will also be changed accordingly.

# String list example

str_list = ['XML', 'PHP', 'Python', 'Java', 'C', 'C++']

print("\nString list contains -> ", str_list)

INTRODUCTION TO PYTHON LISTS : Output

String list contains ->  ['XML', 'PHP', 'Python', 'Java', 'C', 'C++']

In the above example we have changed the position of element XML and the impact is visible in the printed list. So Lists are maintaining the order in which the data are inserted into the list.

NUMBER LIST

Number lists contain all the number elements either Integer or Floating point number.

INTEGER LIST

Integer lists contain all the integer number elements.

# Integer list example

num_list = [4, 6, 2, 10, 15, 20]

print("\nInteger list contains -> ", num_list)

INTRODUCTION TO PYTHON LISTS : Output

Integer list contains ->  [4, 6, 2, 10, 15, 20]

Changing the order of elements

# Number list example

num_list = [10, 15, 4, 6, 2, 20]

print("\nInteger list contains -> ", num_list)

INTRODUCTION TO PYTHON LISTS : Output

Integer list contains ->  [10, 15, 4, 6, 2, 20]

FLOATING LIST

Floating lists contain all the floating point number elements.

# Floating list example

float_list = [5.8, 2.6, 7.8, 6.3, 9.5]

print("\nFloating list contains -> ", float_list)

INTRODUCTION TO PYTHON LISTS : Output

Floating list contains ->  [5.8, 2.6, 7.8, 6.3, 9.5]

BOOLEAN LIST

Boolean lists contains only TRUE and FALSE.

# Boolean list example

bool_list = [True, False]

print("\nBoolean list contains -> ", bool_list)

INTRODUCTION TO PYTHON LISTS : Output

Boolean list contains ->  [True, False]

Changing the order of elements.

# Boolean list example

bool_list = [False, True]

print("\nBoolean list contains -> ", bool_list)

INTRODUCTION TO PYTHON LISTS : Output

Boolean list contains ->  [False, True]

COMBINED DATA TYPE LIST

List in Python can contain elements of different data types as well.

# Combined data type list example 1

comb_list = ['Python', 10, 12, 5.8, False, 'Java']

print("\nCombined list contains -> ", comb_list)

INTRODUCTION TO PYTHON LISTS : Output

Combined list contains ->  ['Python', 10, 12, 5.8, False, 'Java']

In the above example we can see that comb_list variable contains elements of String, Number, Floating number, Boolean data type.

List can also contain another list inside it.

# Combined data type list example 2

comb_list = ['Python', 10, 12, 5.8, False, 'Java', [2, 5, 6], ['XML', 'C++'], [True, False]]

print("\nCombined list contains -> ", comb_list)

INTRODUCTION TO PYTHON LISTS : Output

Combined list contains ->  ['Python', 10, 12, 5.8, False, 'Java', [2, 5, 6], ['XML', 'C++'], [True, False]]

In the above example we can see that comb_list contains other multiple lists inside it. The yellow marked list is a Number list, the blue marked list is a String list and the pink marked list is a Boolean list.

DUPLICACY IN LISTS

Lists in Python allow the duplicate values. A list can contain duplicate elements.

# Duplicacy in list example

# String list example

str_list = ['Python', 'Java', 'C', 'Python', 'XML', 'Java']
print("\nString list contains -> ", str_list)

# Integer list example

num_list = [4, 6, 2, 4, 15, 6]
print("\nInteger list contains -> ", num_list)

# Floating list example

float_list = [5.8, 2.6, 5.8, 6.3, 9.5, 2.6]
print("\nFloating list contains -> ", float_list)

# Boolean list example

bool_list = [True, False, True]
print("\nBoolean list contains -> ", bool_list)

# Combined data type list example

comb_list = ['Python', 10, 12, 5.8, 6, 5.8, True, 'Java', True, [2, 5, 6], [2, 5, 6], ['XML', 'C++'], [True, False]]
print("\nCombined list contains -> ", comb_list)

INTRODUCTION TO PYTHON LISTS : Output

String list contains ->  ['Python', 'Java', 'C', 'Python', 'XML', 'Java']

Integer list contains ->  [4, 6, 2, 4, 15, 6]

Floating list contains ->  [5.8, 2.6, 5.8, 6.3, 9.5, 2.6]

Boolean list contains ->  [True, False, True]

Combined list contains ->  ['Python', 10, 12, 5.8, 6, 5.8, True, 'Java', True, [2, 5, 6], [2, 5, 6], ['XML', 'C++'], [True, False]]

In the above example we can see that every type of list contains duplicate values.
In String list Python and Java both elements are occurred twice.
In Integer list 6 is occurred twice.
In Floating list 5.8 and 2.6 both are occurred twice
In Boolean list True is occurred twice.
In Combined list the highlighted elements are occurred multiple times including list element containing [2, 5, 6].

INTRODUCTION TO PYTHON LISTS : Output

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